When President-elect Barack Obama says he wants to get the US economy moving again, he means it quite literally. Transportation will play a central role in Obama's first months in office, not just for policy changes aimed at improving highway, air and rail travel, but as a road toward economic recovery, energy independence and environmental protection. Solve road congestion, Obama's reasoning goes, and you put people to work. Use less gasoline and help clean the air. Build better trains and move goods more efficiently. Get people out of their cars and reduce greenhouse gas emissions. "We will create millions of jobs," he said recently, "by making the single largest new investment in our national infrastructure since the creation of the federal highway system in the 1950s."